1. Field of the Invention
The invention relates to a method for determining a perfusion image of a portion of a body placed in a static magnetic field by means of magnetic resonance (MR), which method comprises the following steps of:
generation of a control pulse sequence in a first portion of the body and measurement of a control data set by generation of an MR-image sequence for imaging of an third portion of the body to be imaged. PA1 generation of a labelling pulse sequence in a second portion of the body wherein a fluid flows towards the third portion, and measurement of the labelled data set by generation of the MR-image sequence for imaging the third portion of the body, reconstruction of the perfusion image of the fluid in a mass of the third portion of the body from a combination of the control data set and the labelled data set. The invention further relates to an MR apparatus for carrying out such a method. PA1 the third RF pulse being applied according to a third amplitude modulation function and the second frequency modulation function, the third amplitude modulation function being the same as the second amplitude modulation function, but of opposite sign.
2. Description of the Related Art
Such a method is known from U.S. Pat. No. 5,402,785. In the known method, after the control preparation by the control pulse sequence, the control data set is measured from the third portion of the body by the MR image sequences, and after labelling the fluid by the inversion of the proton spins of the fluid by the labelling pulse sequence in the second portion of the body, the labelled data set is measured from the third portion of the body, for example, a slice of the head of a body. From the control data set and the labelling data set, respectively, a control image and a labelled image are reconstructed. The perfusion image is then determined by a combination of the control image and the labelled image, for example by subtraction of the control image from the labelling image. In the known method, magnetisation transfer effects suppress magnetic resonance signals, whereby the rate of suppression varies for different types of tissues and blood. Also magnetic resonance signals from blood, are reduced by the magnetic transfer effects. As a result, the contrast of the perfusion image is affected. In order to reduce magnetic transfer effects in the known method, the first portion and the second portion are positioned symmetrically with respect to the third portion of the body. A drawback of the known method is that geometric restrictions exist in the choice of the third portion of the body.